In general, a vehicle running on a freeway usually runs at a high speed exceeding 100 km/h. Therefore, it is highly probable that a driver of the vehicle may cause a secondary collision with a stopped accident vehicle due to failing to recognize the accident ahead while driving.
In particular, when it is thickly foggy or at night time, visibility is limited. Therefore, even when a driver reduces the speed of a vehicle after noticing an accident vehicle ahead of the vehicle, the secondary collision may unavoidably occur because the braking distance is long compared to the distance to the accident vehicle and thus, the running speed is still high when reaching the accident vehicle.
In addition, even if the visibility is good at day time, the secondary collision may also be caused, for example, on a curved road, by failing to see an accident situation.
Thus, big accidents of chain collisions involving, for example, ten or more vehicles often occur on freeways. However, in the past, no means for preventing such chain collisions have been provided.
In addition, while vehicles are being driven on a freeway, a specific section suddenly becomes a delay or congestion section. Under a situation where the visibility is low, when it is not recognized that the delay or congestion section exists ahead, a rear-end collision may occur even if there is not an accident situation.
While a vehicle is being driven at a high speed on a freeway, a driver of the vehicle may feel sleepy due to monotonous driving. Statics show that about 75% of drivers of vehicles driven on a freeway feel sleepy within 90 minutes after starting the driving. This is because, as a harbinger of sleepiness, the drivers suffer a decline in a cognitive ability for a surrounding situation and hence, for a speed of a vehicle running ahead, compared to the usual care even if the drive is not dozing.
When a vehicle suddenly meets a delay or congestion section while being driven in a smoothly flowing section, the vehicle may not be properly decelerated and thus, rear-end a vehicle driven ahead. An example of a system that can prevent such an accident in advance is disclosed in Korean Patent No. 10-0999812.
However, in the prior art, occurrence of an accident is recognized by a traffic operation center or the like provided in a distance from the accident spot and then, the occurrence of the accident is notified to subsequent vehicles through a display device in the vicinity of the spot of the accident, a radio broadcast or the like. Despite this, an immediate measure may not be taken and thus, a second rear-end collision may not be completely prevented.
In addition, since accidents are sensed merely based on a witness report by a phone, a CCTV image or the like, a notification action of the accident occurrence is unavoidably further delayed when the witness report or the reading or recognition of the CCTV image is delayed. In addition, the accident report by the phone has a problem in that since it is difficult for the witness to accurately describe the accident spot, it is not easy to determine the correct accident spot.